Archery bows are widely used both for target shooting and for use in hunting wild game. To improve the accuracy of the use of archery bows at different distances from the target, various sighting devices have been devised. Compound hunting bows typically are sold with sight holes or attachment points on the bow above the arrow rest for attaching a sight to the bow.
A variety of different types of sighting devices have been developed for use with archery bows, particularly those used for hunting. The most accurate of such prior art sighting devices employ both front and rear sight members which generally include provisions to compensate for the varying amounts of vertical drop or differing trajectories which occur when the selected targets are at different distances from the archer. While most such prior art bow sights improve the accuracy of use of the bow over a bow with no sight at all, significant disadvantages still result. It is difficult, for example, particularly in a hunting situation when the target is present for a relatively short period of time, to eliminate cant from the bow at the time it is sighted on the target and during the release of the arrow.
Patents which are directed to archery bow sights which include front and rear sight elements for improved accuracy, are the U.S. Pat. No. 4,162,579 to James; 4,417,403 to Strange; 4,494,313 to Scott; and 4,542,591 to Montgomery.
The James and Scott Patents disclose front and rear sight platforms which are attached to the bow riser. The rear sight is simply a notch (which is convertible to a circular aperature or "peep" sight in James). The front sight embodies multiple pins located at different vertical spacings corresponding to various distances of the target from the bow. In James, the desired pin must be rotated into place each time a new distance is selected. The rear sight is located in close proximity to the archer's eye and the notch is aligned with the selected bead corresponding to the target distance. It is difficult to accurately align the notch (or the peep hole) with the selected bead, so that this which will permit the archer to eliminate or reduce cant of the bow. Also, in James, the rear sight extends past the string, which presents a problem.
The sight of the Montgomery Patent is similar in some respects to the one of the Scott Patent, but the rear sight is a peep sight which is mounted to the bow riser instead of the string. To use this sight, the bead in the rear or peep sight portion is aligned with a front bead selected to correspond with the shooting distance from the target. A sight of this type is difficult to align under low light conditions; and there is no provision for eliminating or reducing cant in the sight disclosed in the Montgomery Patent.
The fourth Patent of this group is the U.S. Pat. No. 4,417,403 to Strange. The sight of Strange includes a single front bead with a rotatable rear peep sight in which a pair of vertical and horizontal cross-hairs are mounted. The sight disclosed in the Strange Patent may be of some value for target shooting, but it is impractical for hunting. Under hunting conditions where the target distance must be rapidly selected, insufficient time would exist to adjust the rotational position of the rear sight to obtain any accuracy. Once again, there is no provision in the sight disclosed in the Strange Patent for eliminating or reducing cant of the bow.
The U.S. Pat. No. 3,648,376 to Millnamow discloses a sight employing a single bead for the front sight. The rear sight is a telescope with cross-hairs in it. This sight, like the sight of Strange, is impractical for hunting. It is necessary to move the entire sight up a vertical slide bar to set the sight for different yardages. The sight may be applicable for target shooting, but it does not permit rapid and accurate changes for targets at varying distances from the archer. As with the other patents which have been discussed above, the Millnamow Patent does not disclose any provision for reducing or eliminating cant.
The U.S. Pat. No. 4,570,352 to Leal discloses a bow sight, having front and rear sight elements in it, which is intended to be applicable to both target shooting and hunting applications. The rear sight utilizes a pair of vertical and horizontal cross-hairs. The front sight is a staircase configuration, with the different steps of the staircase selected to correspond to different shooting distances from the target. To use this sight, the cross-hairs of the rear sight are aligned on a target and the bow is elevated to place the selected portion of the staircase arrangement of the front sight into alignment with the cross-hairs. The selected step corresponds to the distance of the archer from the target. In contrast to some of the other patents discussed above, the intent of the Leal Patent is to permit rapid selection of the target distance in conjunction with utilization of the sight. It is not necessary for the archer to make any adjustments of the sight in order to effect the distance selection. Since a single fixed staircase notched front sight is employed, independent adjustment of different distances is not possible. Consequently, it appears that this front sight must be selected for a particular bow and also is capable of optimum function only within a limited arrow speed. The selection of the desired one of the various staircase steps under hunting conditions, where quick selection of the right point is imperative, also may be difficult. As with the other patents, there is no provision in the sight of the Leal Patent to minimize or eliminate cant of the bow.